1. Field of the Invention
The present invention relates to a method of and apparatus for determining the body weight of animals and the development of plants housed in a controlled environment within an enclosure,
2. Background Information
In the rearing of animals such as pigs and poultry it is known to rear the animal in an enclosure with a tightly controlled environment. Indeed many types of food are also produced in these enclosed environments. Usually the animals reared are of a uniform genetic type. In rearing such animals the producer is attempting to optimise the food conversion ratios minimise energy arid other overhead costs and effectively to determine the optimum time for removing all or some of the animals for subsequent processing. The elements of successful production is the control of the environment and all the other conditions prevailing.
Plants are grown in substantially the same way and thus it is not uncommon for people engaged in intensive animal rearing to refer to them as crops. Thus in this specification the term crop is used to encompass animals and plants. While the invention described herein is particularly relevant for the determining of the body weight of animals housed in a controlled environment within an enclosure, the method and apparatus is equally well adapted to the determination of the body weight or more strictly the development of plants since in many cases the development or maturity for harvesting of a plant is not determined by its weight and thus the general terms xe2x80x9ccropxe2x80x9d and xe2x80x9cdevelopmentxe2x80x9d are used.
An example of animal rearing is in the production of poultry. The birds, which are usually of a uniform genetic type in that they are generally bred from a common grandparent stock thus start off as almost totally uniform animals. The producers then try to provide the optimum environmental conditions for effective growth and general welfare. The producer has a maior problem in that the producer wants to have the optimum average bird weight when the poultry is about to be slaughtered so that the best price can be obtained. Since in moat cases the price paid is based on average bird weight it is essential to know exactly what the weight is. Further because buyers such as supermarket chains tend to pay a fixed price based on minimum bird weight the need to be able to ascertain the average bird weight is all important.
Feed forms the single largest factor in the cost of production being of the order of 60% of the total overall cost and thus optimising the feed conversion ratio is the single most important factor in the financial health of the operation. Thus knowing the correct time to remove the animals for further processing, often referred to as harvesting, is vital and this is when the bulk of the crop has met the target weight criteria. This is irrespective of the target weight criteria.
In poultry production a number of methods are used to determine the weights. The first method is a simple manual sampling method in that workers move through the birds with weighing scales and sample the crops by hand. This method produces a relatively accurate assessment of the average bird weight. However, it is labor intensive and thus costly to collect the information manually and then correlate the collected data into an electronic data base.
The second method is to provide electronic weighing platforms at various points throughout the production area. These platforms take weight measurements as birds climb on and off them. While this method is more suitable for automatic electronic capture analysis on data transmission it suffers from the disadvantage that is dependent on animal behaviour. Unfortunately the same animals tend to mount the weighing platform over and over again so that accurate sampling cannot be guaranteed. Further the actual weighing scales or platforms are relatively expensive and a significant number of platforms are required so that the total cost of this method is also high.
Objects
The present invention is directed towards providing an improved method and apparatus for determining the development of plants and the average body weight or average gross body weight more correctly of a number of animals housed in an enclosure within a controlled environment.
According to the invention, there is provided a method of determining the development of a crop housed in a controlled environment within an enclosure including the acts of analysing and measuring the gas constituents of the environment before and after a preset time to determine the change in the concentration of one or more gases during a test period to estimate the metabolic rate of the animals and hence their weight.
Preferably, the increase in the quantity of carbon dioxide or the decline in the quantity of oxygen is measured. It has been found that depending on the metabolic activity of the animals, the CO2 gas emission varies with body weight for animals and with plant development generally. CO2 and O2 are good control gases. It will be appreciated that this is a much more efficient and dynamic way of measuring crop development than methods used heretofore, such as, for example, sample weighing.
Ideally, the enclosure is sealed during the test period and preferably the air is recirculated within the enclosure during the test period.
It is also advantageous to cause the environment within the enclosure to assume a rest phase with minimal crop activity. In this way, no extraneous factors are impinged on the test results. Since rest periods occur naturally during certain times of rearing, particularly night time which is largely for staff convenience, this is a time within which the test may be conveniently carried out. It is envisaged that the metabolic rate of the crop will need to be compared to the actual weight for animals or some other assessment criterion for plants to calibrate the measurements. It is also envisaged that prior to final removal of the crop from the enclosure, the metabolic rate of the crop is taken and the development estimated and on removal and further processing, the development is measured to provide more accurate correlation of metabolic rate with development for future control.
It is envisaged that with the present invention, the gas constituents in the air being removed from the endosure are measured to enable the control of the air input for optimal environmental conditions. In this way, further control of the growing environment may be provided. It is also envisaged that the control of the development of the crop, whether it be the growth of poultry or the development of plants, may be accurately controlled so that when it is known that there will be periods of greater demand, the crop can be developed quickly to achieve the right weight and development at the target time. Alternatively, when it is known that there is a drop in demand, than the general development can be slowed down. This can be done by:
dividing the expected crop rearing time into a plurality of control periods;
determining the development of the crop at the end of each control period; and
varying the growing conditions for the next control period to take account of the previously recorded development to obtain a desired development gain for the next control period.
In this latter method, to determine the optimum growing conditions including environmental conditions and food quantities and type to obtain the desired development gain, the steps are performed of carrying out a number of tests on separate samples of crops for each control period comprising:
varying the environmental conditions and food quantities and types for the control periods to provide a rearing condition;
obtaining the crop development for each control period and rearing conditions; and recording the rearing conditions and development gain for each control period to provide the optimum growing conditions for a specific control period having regard to initial each development at the start of the control period and desired crop development at the end of the period.
It is also envisaged that the methods according to the present invention will allow more accurate determination of optimum growing conditions. In addition to measuring the gas constituents of the environment for weight and other measurement, the gas constituents are measured during the growing period and the measurements used to control the air intake into the environment for optimum growing conditions.
Further, the invention provides a crop roaring house of the type comprising an enclosed room and means for controlling the environment including at least controllable air vents and healing means in which there is provided a gas sensor for determining the concentration of selected gases in the environment. Ideally, the gas sensor includes CO2 and/or O2 sensing means.
Ideally, there is an air recirculation fan and the gas sensor is mounted in the path of the air flow of the fan.
In one embodiment of the invention, the crop rearing house includes a monitoring unit comprising:
an airtight enclosure;
a plurality of air monitoring sensors;
an inlet for ambient air;
an inlet for rearing house air;
fans to control the intake of air into the unit; and
control means to regulate the operation of the fans and sensors.